Chemical set sand molds are commonly used in the casting of aluminum, brass, bronze, and iron products. For example, major automotive manufacturers typically use chemical set sand in their foundries. To prepare chemical set sand, the sand undergoes a “mulling” process in which various binding agents (e.g., various clay and chemical additives) are blended with the sand, which results in a mixture (i.e., chemical set sand) which is suitable for the sand molding process.
To form a mold, the prepared sand mixture is manually compressed around a pattern. After packing, the chemical set sand is allowed to set, or bond, so that it will maintain its shape throughout the remainder of the casting process. In this way, the blended sand and binders are compacted around the pattern and take on the shape of the desired casting, as is well known in the art.
As is also well known, the cavity in the sand is formed by a pattern (i.e., an approximate duplicate of the object to be cast), which is typically made out of wood, plastic or sometimes metal. The pattern is positioned in a box (known as a flask) into which the sand is placed. Accordingly, the cavity is contained in the sand in the flask after the sand has been packed around the pattern.
In a two-part mold, which is typical of sand castings, the upper half, (i.e., including the top half of the pattern) is called the cope and the lower half is called the drag. Typically, the drag is formed, after which the cope is formed. (Those skilled in the art would be aware that the cope may be prepared first.) After the cope and the drag are formed, the cope is positioned on top of the drag, aligned with the drag.
If the object to be cast is intended to be hollow, then a core is positioned in the cavity in the drag (i.e., before the cope is positioned on the drag), as is known.
In the prior art, the flask is filled (e.g., using a five-gallon pail), e.g., sand is placed around the pattern. Subsequently, a vibrator is positioned on the cope, and the cope is vibrated. When the sand is set, the cope is then rotated through approximately 180°.
The cope is then positioned on the drag. In the prior art, the rotation and the positioning of the cope are done manually. Because of the weight of the sand, two workers are needed. Also, because the cope and the drag are relatively heavy and need to be substantially vertically aligned, the task of positioning the cope on the drag is somewhat time-consuming and difficult.
In the prior art, up to 12 molds can be produced in one day using chemical set sand. However, as indicated above, the prior art process is relatively labor-intensive. The prior art process requires two people to set up the flask and place the pre-mixed chemical set sand in the mold, which is then allowed to cure, or harden. Each mold weighs 300 to 400 pounds. As described above, in the prior art, the drag and the cope are required to be moved and placed together relatively precisely. This manual process limits the number of units which can be produced per day due to the physical requirements, e.g., two people are required to rotate and position the molds, and time must be allowed for the binders in the sand to set.